How do doctors figure out if someone is a candidate for GLP-1 medication versus just needing lifestyle changes?

It generally comes down to BMI thresholds combined with whether there are weight-related health conditions present. Clinical guidelines typically consider GLP-1 medication for adults with a BMI of 30+ on its own, or a BMI of 27+ with at least one weight-related condition like high blood pressure, type 2 diabetes, or sleep apnea. Lifestyle changes (diet, activity, sleep, stress) are usually recommended alongside medication rather than as a strict "try this first" gate, but for people with lower BMI and no related health conditions, medication is less likely to be the first recommendation. References: https://obesitycanada.ca/healthcare-professionals/adult-clinical-practice-guideline/